This study analyzed the relationship between neonatal serum TSH levels at 7–14 days after birth and factors such as sex, GA, birth weight, age at the first serum thyroid function test, maternal age, maternal TSH and FT4 levels in early/late pregnancy, whether the mother took thyroid-related medications (LT4 and antithyroid medications), whether the TPO antibody was positive during pregnancy, and whether the mother had gestational diabetes mellitus or gestational hypertension/preeclampsia. This evidence concerns the gene TPO and gestational diabetes.